94 results about "Radar equation" patented technology

The invention relates to an airborne SAR radiation external calibration processing method based on weak arrangement of corner reflectors. The method comprises the following steps: obtaining original SAR image data of a calibration field; on the basis of a point target radar equation, reconstructing an radiation external calibration equation; performing stable estimation on calibrator image energy and geometric optical solution on a calibration RCS; carrying out fitting and correcting on a radar system transfer function to obtain preliminary radiation calibration SAR image data; carrying out the stable estimation on the calibrator image energy and the geometric optical solution on the calibration RCS; and estimating a system constant item so as to generate calibration data and obtain final radiation calibration SAR image data. According to the invention, on the basis of the point target radar equation, according to the characteristic of parameters of a radar system, the SAR radiation external calibration equation comprising a change system transfer function and a constant system constant item is reconstructed, the application process of radiation external calibration is simplified, and the problem is avoided that it is quite difficult for airborne SAR flight to obtain a large-scope homogeneous stable tropical rainforest area frequently used by similar spaceborne SAR radiation calibration.

The invention provides a method for optimizing laser radar detection atmospheric composition spectral line analysis, through building of an IPDA laser radar equation of hard target reflection, calculation of difference optical thickness of two pulses and CO2 air column mixing rate XCO2 with a weight, single spectral line broadening calculation, absorption cross section calculation, CO2 absorption optical thickness calculation, a weight function profile and a CO2 molecule number density profile, weight function-optimized spectral lines are obtained. The spectral lines obtained by the method have a higher lower-atmosphere weight ratio, and detection is closer to a true value.

The invention provides a method for evaluating the influence of speckle coherence on the ranging accuracy of a single-photon laser radar. The method comprises the steps of setting the parameters of the single-photon laser radar system, calculating the autocorrelation function of a receiving aperture of the single-photon laser radar system and the normalized covariance function on the intensity ofthe receiving aperture to calculate the speckle degree of freedom M; calculating the average signal photon number Ns according to the laser radar equation, and calculating the total noise rate Nn of the laser radar system; differentiating time through the detection probability based on the root mean square pulse width [Sigma]s of the laser pulse to obtain the detection probability density functionfs(t) of the echo signal with respect to time t, and obtaining the mean value shown in the description and the variance Var of the time when the detector detects the target point; and obtaining the influence of the speckle coherence on the ranging accuracy of the single-photon laser radar according to the drift error Ra and the random error Rp. The invention has good compatibility, can provide guidance for the system parameter design of the laser radar, improve the detection probability and reduce the ranging error as much as possible under the restraint of satisfying the false alarm probability.

The invention relates to a laser radar echo signal de-noising method based on variational mode decomposition. The method comprises the steps of according to a laser radar equation, simulating a laserradar echo signal; selecting an optimal decomposition layer number K in variational mode composition by means of detrended fluctuation analysis; performing variational mode decomposition on the laserradar echo signal; then calculating similarity between the laser radar echo signal and each mode probability density function after decomposition through Bhattacharyya distance, differentiating a correlation mode and an uncorrelated mode; then processing the uncorrelated mode by means of a moving average mode, and extracting a related signal; and finally reconstructing the correlation mode and theprocessed uncorrelated mode for realizing de-noising of the laser radar echo signal. The laser radar echo signal de-noising method can effectively filter the noise in the laser radar echo signal andimproves effective detecting distance and precision of the laser radar.

A method for recognizing a vertical misalignment of the radiation characteristic of a radar sensor of a control system for a motor vehicle, in particular of a driving speed and/or adaptive driving speed system, including the following steps: the receive power of the radar radiation reflected from an object is determined; the distance dependence and the horizontal angular dependence are compensated according to the radar equation; the functional dependence of the receive power, processed in this way, on the distance from the object is compared to an expected and stored curve of the receive power over the distance, and from this the vertical misalignment of the radiation characteristic of the radar sensor is inferred.

The invention discloses an atmospheric aerosol optical property measuring method and a laser radar system which is high in spectral resolution. By locking the laser emission frequency, the function of the laser radar system which is high in spectral resolution is achieved. According to a Fabry-Perot interference narrowband spectral filter, an aerosol scattering component and a molecular scattering component are separated, the difficulty that in a traditional back scattering laser radar, one radar equation is utilized to invert two unknown quantities, namely a aerosol scattering coefficient and an extinction coefficient is appropriately solved, limitation of the emission laser wavelength do not exist, the measured atmosphere back scattering ratio is high in accuracy, and the relative error is small.

The invention provides a multiple missile collaborative ballistic planning method to deal with penetration. The method comprises the specific steps that step 1, based on the radar equation, a radar threat quantification model is established to describe the threat of a radar detection area to a missile; step 2, a collaborative control model is established, the collaborative control model comprisesa collaborative time control model and a collaborative angle control model; step 3, a collaborative attack problem is converted into a nonlinear optimal control problem which is solved based on a hp-self adaptive Radau pseudospectral method, which means at one moment of the flight, the remaining flight time of each missile is determined, whether or not a collaboration is necessary, if necessary, the time for the collaborative attack is calculated and the missile to be adjusted is determined, and the collaborative ballistic planning is conducted on the missile needs to be adjusted. According tothe multiple missile collaborative ballistic planning method, multiple missiles attacking a target on the same attacking time and with the same attacking angle is ensured; meanwhile, the radar detection threat is smallest during the flight, and the comprehensive combat effectiveness is effectively improved.

The invention discloses a method for measuring aerosol parameters by a lateral laser radar based on a CCD (charge-coupled device) imaging technology. The method comprises the following steps of: firstly, selecting a phase-comparison function value of aerosol to atmospheric molecules of a reference point in a horizontal direction; determining and affirming that a backscatter coefficient value of the aerosol on the reference point is equal to that at each scattering angle; inserting the drift angle (theta) and the angle width (dtheta) with each pixel of a CCD camera, and the vertical distance (D) between the CCD camera (3) and a beam (5) emitted by the laser radar into a lateral laser radar equation shown in the description; taking the adjacent point as a new reference point after solving the phase-comparison function of the aerosol on the adjacent point from the value, gradually solving until a profile of the phase-comparison function of the aerosol is obtained; then affirming that the obtained phase-comparison function value of the aerosol in the horizontal direction is equal to that in the vertical direction, measuring the backscatter coefficient value of the aerosol at one height as the reference point, and obtaining the profile of the backscatter coefficient value of the aerosol by adopting the method. Therefore, the aerosol parameters conforming to the actual condition can be measured.

The invention discloses a high spectral polarization atmosphere detection laser radar system and a control method. The high spectral polarization atmosphere detection laser radar system comprises a laser emission system, a photoelectric reception/detection system and a multichannel data collection system; the multichannel data collection system is connected to the laser emission system and the photoelectric reception/detection system; through the high spectral resolution raster and a Fabry-Perot interferometer, the high spectral polarization atmosphere detection laser radar system realizes the high spectral high resolution detection function. The high spectral polarization atmosphere detection laser radar system separates the molecule scattering component in the atmosphere echo signal from the aerosol scattering component through the Fabry-Perot interferometer, solves the difficulty, which is met by a traditional backscattering laser radar, in inversion of two unknown quantities including an aerosol scattering coefficient and an extinction coefficient performed by a radar equation. The high spectral polarization atmosphere detection laser radar system can realize the detection of multiple atmosphere parameters, has a high automation level, a simple structure design and strong expandability and can provide the application service for the atmosphere research and atmosphere protection.

The invention discloses a method for simulating distributed type MIMO sky wave beyond visual range radar sea clutter, and belongs to the field of radar radio wave propagation. An existing simulating method is mainly suitable for a sky wave beyond visual range radar of a traditional (standard) single base or a double-base ground-wave radar but not suitable for the situation of a distributed type MIMO sky wave beyond visual range radar, and not all physical factors are taken into consideration. The method is suitable for the situation of the distributed type MIMO sky wave beyond visual range radar, the geometrical relationship between the incidence direction and returning scattering direction of receiving and sending channels relative to the sea surface of the observing area is calculated based on digital ray tracing, and the scattering sectional area expression of normalization of double-base one-order and two-order sea clutter of all the receiving and dispatching channels is inferred; after the scattering sectional area expression and the Doppler transfer function of a receiving and dispatching propagation path are convoluted, the sea clutter power spectral density of the receiving end is obtained based on the radar equation; lastly, the random time sequence of sea clutter and noise at the receiving end is obtained according to the power spectral density. According to the simulation method, the factors affecting the distributed type MIMO sky wave beyond visual range radar sea clutter are fully taken into consideration, precision is high, universality is good, and the method has popularization and application value.

The invention discloses a method for calculating the farthest detection distance of a Gm-APD laser radar. The method comprises the following steps: 1, acquiring echo intensity by using a laser radar equation; 2, obtaining the triggering probability of each time interval of the Gm-APD laser radar; 3, acquiring simulation data under different statistical frame number conditions by using a Monte Carlo method; 4, echo parameters are obtained through a signal detection method according to the Gm-APD trigger probability curve obtained in the step 2 and the simulation data obtained in the step 3; and5, calculating echo detection probability and confirming optimal parameters of the system. The Gm-APD performs optimal argumentation on parameters such as laser parameters and optical aperture underthe condition that the index parameters are determined, so that the laser radar system realizes optimal power consumption and volume on the premise of meeting the indexes, and has a very important promotion effect on further engineering of the Gm-APD laser radar.

The invention provides a calibration method. According to the calibration method, an active calibrator is utilized for calibrating the deviation generated when an on-track radar height gauge measures the scattering cross section of a point target. The calibration method includes the steps of defining a calibration factor beta, wherein Pt_alti multiplied by Falti (0, 0)<2> and Galti_sys_point is beta, Pt_alti is transmitting power of the height gauge, Falti (0, 0) represents a power gain corresponding to an antenna of the height gauge in the largest radiation direction, and Galti_sys_point represents power gains provided by other parts, except for the antenna, of the height gauge; obtaining the scattering cross section of the point target according to the calibration factor beta, the receiving power of the height gauge and a radar equation, and completing calibration. The calibration method has the advantages that the active calibrator used in the method is of a single antenna structure, the cost and errors of directional diagram measurement through double antennas are reduced, information of an antenna directional diagram of the height gauge and information of an antenna directional diagram of the calibrator are included in receiving data of the height gauge and receiving data of the calibrator respectively, and calibration can be completed according to the calibration method without providing the information of the antenna directional diagram of the height gauge and the information of the antenna directional diagram of the calibrator independently.

The invention discloses a laser radar system and a laser radar method for detecting concentrations of CO2 (Carbon Dioxide) in atmosphere. An ON wavelength laser device of the laser radar system does not adopt a conventional active frequency stabilization technology, but adopts a passive frequency stabilization and frequency modulation technology, the change of an echo signal of an ON laser reflects the intensity change of an echo caused by the frequency modulation during a shortest time, a minimal value of a period reflects an echo signal of the wavelength at a CO2 absorption peak at this moment, and the echo signal and a signal obtained by an emitted energy monitoring photoelectric detector are conducted for normalization processing, namely, the intensities of ON and OFF wavelength echo signals can be accurately obtained, and the concentrations of the CO2 in atmosphere can be inverted by a differential absorption laser radar equation. By using the method, the measuring precision of the system can be improved, and the complexity of the system can be simplified.

The invention relates to a waveform design for a double-cycle pinch-off type pseudo-random code and a signal processing method for an echo. The waveform design for the double-cycle pinch-off type pseudo-random code and the signal processing method for the echo is characterized in that the needed radar signal-transmitting time width is computed combined with a radar equation, codon time width of random codes of a first group, the digit of the random codes and subcode time width when a wave form is pinched off are ascertained. An echo signal after analogue-to-digital sampling is finished under despreading and spread spectrum and section matched filtering is carried out. The result of the section matched filtering is under fast fourier transform (FFT) treatment, the constant false alarm rate (CFAR) technology is utilized, and a target is detected in a velocity dimension and a distance dimension. The waveform parameters of random codes of a second group are ascertained to cover a dead zone. Target data obtained through the first group and the second group are mixed to discover and complement the dead zone. The waveform design for the double-cycle pinch-off type pseudo-random code and the signal processing method for the echo has the advantages of being short in instantaneous pulse width and high in waveform duty ratio, short in distance of the dead zone, small in transmitting power and time sharing in receiving and dispatching.

The invention relates to a broadening correcting method of atmospheric pressure for differential absorption atmospheric CO2 laser radar. The broadening correcting method is characterized in that a correction formula which is sensitive to the wavelength is adopted to calculate Lorentz full width at half maximum (FWHM); considering both the broadening factor and the independence of temperature related index, the problem of a mixture ratio dynamic value of high altitude CO2 is solved by adopting two ideas of direct value taking and iteration solution; and the ratio x, namely differential absorption laser radar equation concentration solution, of CO2 molecule concentration and volume is transformed. With the adoption of the broadening correcting method, the uncertainty of taking values of the classical algorithm is abandoned to the maximum extent so as to avoid bringing new errors; meanwhile according to the experimental scene demands, the method of specifically adopting value taking solution or iteration has the advantage of flexibility and has good application prospect and great development potential in the field of differential absorption laser radar for detecting atmospheric CO2.

The embodiment of the invention provides a gas particulate matter measuring method and device. The gas particulate matter measuring method comprises the following steps: measuring gas particulate matters through a laser radar to obtain radar echo signal strength; determining light extinction coefficients of a molecule and backscattering coefficients of the molecule; inputting the radar echo signal strength, the light extinction coefficients of the molecule and the backscattering coefficients of the molecule into a preset discrete laser radar equation and calculating to obtain particulate matter concentration intermediate parameters; inputting the particulate matter concentration intermediate parameters into a preset polynomial regression equation and calculating to obtain particulate matter concentration. According to the gas particulate matter measuring method and device provided by the embodiment of the invention, as the particulate matter concentration is obtained through the preset discrete laser radar equation and the preset polynomial regression equation, the large range and high precision measurement of the particulate matter concentration can be realized only through the laser radar, and a PM measuring instrument is not required to be used, so that the quantity of used instruments during measurement is reduced, and the cost is reduced.

The invention relates to a satellite-borne GNSS-R high-precision soil moisture estimation method based on CYGNSS data, and the method comprises the steps: obtaining a plurality of groups of satellite data through CYGNSS, and carrying out the preprocessing of the data, and obtaining standard data; processing the standard data by using a bistatic radar equation to obtain a first surface reflectance; inputting a satellite elevation angle corresponding to the water area into a Fresnel reflection equation, and calculating to obtain a reflectivity gamma water; screening out a first surface reflectance SRwater of the water area, obtaining a system error correction coefficient by using a formula, and correcting the first reflectance of the land area based on a formula SR1 = SR * Rcali to obtain a second reflectance; correcting the second surface reflectance according to the vegetation optical depth and the surface roughness to obtain a third surface reflectance; acquiring a third surface reflectance of the soil in the target area, and inputting the third surface reflectance into the soil moisture estimation model to obtain a soil moisture estimation value of the target area; according to the invention, a method for correcting system errors, surface roughness and vegetation is provided through CYGNSS data, and the soil moisture estimation precision is improved.

The invention relates to a method for analyzing radiation properties of high-resolution SAR (synthetic aperture radar) satellites, and belongs to the technical field of overall designs of SAR satellites. The method has the advantages that radiation property indexes of various satellite-borne SAR working modes are accurately computed, and system design results are inspected and rechecked for the high-resolution SAR satellites and the high-resolution SAR satellites in variable-repetition-frequency modes in particular; echo signal energy starts to be computed point by point along imaging time from single-pulse radar equations, accordingly, time-dependent variation conditions of antenna gain, ground-object back-scattering coefficients, slope distances and radar scattering areas of the SAR satellites can be sufficiently reflected, accurate imaging echo signal energy can be obtained, and the accurate radiation property indexes of the high-resolution SAR satellites further can be obtained.

The invention discloses a two-dimensional resource allocation method for networking radar multi-target ISAR imaging, relates to the technical field of phased array radar inverse synthetic aperture radar imaging, and solves the technical problem of how to reasonably allocate time and aperture resources of a radar system for a multi-target imaging task under a radar networking condition so as to improve the overall performance of the radar system. According to the method, on the basis of target feature cognition, requests for radar resolution are determined, time and aperture resources requiredby target imaging are determined by combining a sparse ISAR imaging technology and a radar equation on the basis; and then resource allocation of the networking radar system is realized through a two-dimensional resource scheduling model for multi-target imaging of the distributed networking radar system, and finally, a multi-radar to multi-target inverse synthetic aperture imaging task is realized through alternate observation and acquisition of target echo signals. According to the method, resource allocation is considered from two perspectives of time and aperture, the resource utilizationrate is improved, and the overall performance of the system is improved.

The invention provides a radar cross-section (RCS) estimation correction method for a target based on water vapor absorption loss. On the premise that the detection distance and a detection radar are determined and the detection frequency is known, the RCS estimation correction method for K wave band targets and millimeter wave band targets is provided according to relevance between the water vapor absorption loss and a radar equation so as to provide reference for remote sensing and detection of the target in a water vapor absorption environment.